radar@cd.chalmers.se (10/04/90)
I have been reading this group for a while and have decided to put this question on the net. When and by whom was the 19" rack standard invented ? I do not know if this is the right forum to ask this question but since the telecom history goes back more than 100 years it is worth a try. With best regards, Klas Nordstr|m radar@cd.chalmers.se
tjrob@ihlpl.att.com (Thomas J Roberts) (10/05/90)
From article <13001@accuvax.nwu.edu>, by radar@cd.chalmers.se:
> When and by whom was the 19" rack standard invented ?
As this is a telecom newsgroup, I feel compelled to mention that AT&T
equipment racks [5ESS(Tm)] are usually 22.5" wide. NTI racks can be
24" or 44" (?) wide. [These are the widths of the card cages, overall
width is somewhat larger.]
"The best thing about standards is that there are so many of them."
Author Unknown
Tom Roberts
AT&T Bell Laboratories
att!ihlpl!tjrobhaynes@ucscc.ucsc.edu (99700000) (10/08/90)
Let's get nit-picky about trivia. :-) In article <13072@accuvax.nwu.edu> 0004133373@mcimail.com (Donald E. Kimberlin) writes: >you have need for specifications in the U.S., the Electronic >Industries Association (EIA) published a standard many years ago. If I remember from an old issue of the Radio Amateur's Handbook that there was at one time both a Western Electric 19" standard and a RETMA 19" standard. RETMA (well before that it was RMA - Radio Manufacturers' Association - was the predecessor name to EIA) The WECo standard was strictly multiples of 1-3/4" panels with notches 1/4" in from the edges: so the holes are spaced 1/2; 1-1/4; 1/2; 1-1/4; 1/2 and so on. The RMA standard had additional holes in the iddle of the 1-1/4" intervals. So most racks you get today have a spacing 1/2; 5/8; 5/8; 1/2; 5/8; 5/8; 1/2 and so on. >BTW, 19 inches is not the only "standard." Bell electronics equipment >most commonly uses 23 inch racks, while "frames" of electromechanical >switching equipment mount in 30 or even 36 inch widths, all using the >same 1-3/4 inch vertical increments. I don't know about the 30 and 36 inch stuff; but the Bell 23-inch racks have a standard based on 2-inch vertical increments; or maybe it's integral multiples of 1 inch. I belive the EIA standard also allows for a 24-inch rack, as I've seen some of those in catalogs. I'm dubious about any Western Union connection with all this, because I've seen some Western Union equipment that doesn't fit on 19" racks. But I'm equally eager to learn the True History of this peculiar 19" dimension that has ruled the lives of so many of ur for so long. haynes@ucscc.ucsc.edu haynes@ucscc.bitnet ..ucbvax!ucscc!haynes
wb8foz@mthvax.cs.miami.edu (David Lesher) (10/08/90)
Somewhere in the backs of long unaccessed core, I seem to dredge up the fact that 19" racks was a Western Onion standard. Lending credence to that is the fact that Ma's is *not* 19", and we all know that Ma never used competitor's standard, especially a successful one. By the way, the standards quote is from Andy Tannenbaum, author of Minex and doer of many other things... wb8foz@mthvax.cs.miami.edu (305) 255-RTFM